src/keepalive.c - master - niceSOFT/libssh2

src/keepalive.c
97 строк4 KB
Viktor Szakats
src: use abstract internal time type, bump resolution to milliseconds
19 июл 2026, 03:56
19 июл 2026, 03:569c42176
/* Copyright (C) Simon Josefsson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include "libssh2_priv.h"
#include "transport.h" /* ssh2_transport_write() */

/* Keep-alive stuff. */

void libssh2_keepalive_config(LIBSSH2_SESSION *session,
                              int want_reply,
                              unsigned int interval_s)
{
    if(!session)
        return;

    if(interval_s == 1)
        session->keepalive_interval = ssh2_sec_to_timediff(2);
    else
        session->keepalive_interval = ssh2_sec_to_timediff(interval_s);
    session->keepalive_want_reply = want_reply ? 1 : 0;
}

int libssh2_keepalive_send(LIBSSH2_SESSION *session, int *seconds_to_next)
{
    ssh2_time_t now;

    if(!session)
        return LIBSSH2_ERROR_BAD_USE;

    if(!session->keepalive_interval) {
        if(seconds_to_next)
            *seconds_to_next = 0;
        return LIBSSH2_ERROR_NONE;
    }

    now = ssh2_now();

    if(now >= session->keepalive_last_sent + session->keepalive_interval) {
        /* Format is
           "SSH_MSG_GLOBAL_REQUEST || 4-byte len || str || want-reply". */
        unsigned char keepalive_data[] =
            "\x50\x00\x00\x00\x15keepalive@libssh2.orgW";
        size_t len = sizeof(keepalive_data) - 1;
        int rc;

        keepalive_data[len - 1] = (unsigned char)session->keepalive_want_reply;

        rc = ssh2_transport_send(session, keepalive_data, len, NULL, 0);
        /* Silently ignore PACKET_EAGAIN here: if the write buffer is
           already full, sending another keepalive is not useful. */
        if(rc && rc != LIBSSH2_ERROR_EAGAIN) {
            ssh2_err(session, LIBSSH2_ERROR_SOCKET_SEND,
                     "Unable to send keepalive message");
            return rc;
        }

        session->keepalive_last_sent = now;
    }

    if(seconds_to_next) {
        ssh2_timediff_t to_next = ssh2_timediff_to_sec(
            session->keepalive_interval +
            (session->keepalive_last_sent - now));
        *seconds_to_next = (int)SSH2_MIN(to_next, INT_MAX);
    }

    return LIBSSH2_ERROR_NONE;
}